Electromagnetically operated pretensioned contact spring



Dec. 6, 1949 F. X. REES 2,490,289

' ELECTROMAGNETIGALLY OPERATED PRETENSIONED CONTACT SPRING Filed Feb. 9, 1946 13 14 12 FIG. 1.

7 0 AT f g ml l-nventor t 'orneg Patented Dec. 6, 1949 ELECTROMAGNETICALLY OPERATED PRE-r TENSIONED CONTACT SPRING Frank X. Rees, Chili, N. Y., assignor to General Railway Signal Company, Rochester, N. Y.

Original application March 29, 1944, Serial No.

528,556, nowgatent No. 2,425,562, dated August 12, 1947'. Divided and this application February- 9', 1946, Serial No. 646,632

6 Claims. 1

This invention relates in general to relays of the electromagnet type, and has more particular reference to an improved for-mot code following relay, adapted more particularly for use in connection with railway operation.

This application is a division of my prior application Ser. No. 528,556, filed March 29-, 1944, now Patent No. 2,425,562, dated August 12, 1947.

The relay of the present invention is an improvement in the form of relay disclosed in the Field application, Ser. No. 351,003, filed August 3, 1 940, for Relays, now Patent No. 2,360,644, dated October 17, 1944.

In the operation of relays of the type to which the present invention relates, there is a tendency upon movable contacts striking against fixed con tacts, to vibrate and bounce for a short'period of time, during which time the control circuits are not effectively made, and during which time there is excessive arcing at the contacts and burning of the points. This is particularly the case ifthe contacts carry heavy currents and the relay is energized at a low level in the interest of economy in operating costs. As a result, this faulty type of operation materially decreases the useful life of the relay contacts and reduces the efficiency and economy of operation and maintenance.

With the above and other considerations in mind, it is proposed in accordance with this invention, to provide a. relay in which these defects a ry ar l ob ia ed- One of the objects of the present: invention is to produce a relay wherein the movable contacts do not bounce or vibrate on the fixed contacts,

whereby to vastly improve th operating characteristics of relays of this type.

Another object of the present invention is to produce an improved, yet simple, form of adjustins means tor the air gap; between the, armature and certain of its cooperating pole pieces.

Further. objects, urp s s and characteristic features of this invention will. appear as, the description progresses, referencebe'ing: made to the accompanying. drawings showing, solely by way of example, and. in. no manner whatsoever in a limiting sense, one form which the invention can assume.

In the drawings:

Fig. 1 is a fragmentary sectional view, with parts shown in elevation, of a-rclay constructed in accordance with the present invention.

Fig. 2 is a fragmentary view of. a detail of construction.

Fig. 3- is a fragmentary View, with parts shown in section. as air ap actuati means.

Figs. 4-9 are fragmentary views showing various operative posit-ions of the relay contacts.

Fig. is a. View showing operative characteristics of a, relay in accordance with thisinvention.

Fig. 11 is a View showing oscillograms of cur rent conditions in a conventional relay and in a relay in accordance. with the present invention.

Referring now to, the drawings, a, fragmentary portion of a relay, in accordance With this invention, is shown in Fig. 1.. Only such parts of the relay will be described as. are necessary for a complete understanding of this invention. The relay is shown as. of the polar neutral type, butcan, or course, be of any other type, and is biased by spring means to makeup itsback contacts, whereby it responds only. to current of a particular polarity, to move. its movable contact fingers so as to make up its front, points, This operation is the same as set: forth in the Field application, above referred to.

The relay includes a top plate; TP, on which are supported the, electromagnetic operating means l2 and [3,, and the. permanent magnets M. The relay includes an armature l5, cooperating with the electromagnct. pole pieces [5; and ll, and the permanent magnet pole pieces or shoes, I 8 and [9. The armature, rocks on, a bearing comprising a hardened bearing block 20, extending across the permanentmagnet pole shoes and received in slots in the, shoes, as shown at 21- and 2 2' (Fig. 3). Between the block and the armature, and received in a V:-shaped slot in the armature, is a cylindrical pivot rod 24.

The armature is shown in its spring biased position, that is, rocked clockwise so as to bear against the electromagnet-pole shoe I! by adjustable spring bias, means 53 and 54. The armature is supported by a spring supporting means suitably carried by-, and, adjustable on, a support: arm 26, carried bythe to plate.

Connected; to, and carried, by, the armature is an operating arm, 21;, having one end fastened to the armature, as by bolts 2-8: and 28. The operating arm 21 terminates, at its outer end, in a tong-like jaw having; an upper; portion 30, and a lower portion 3|, whiclrjawreceives, and holds in compressed, pretension fashion, spaced contact fingers 32 and 3 3.

These contact fingers 318416133 constitute movable fingers which, are; operated by the jaw portions as and 3!, by means of the armature of the relay, and cooperate with fixed contact fingers 35 and 36. Th contact fingers 35 and 35 carry contact points 37 and: 38, and are backed up by adjusting screws 39 and 40 carried by stiff, ab,-

solutely rigid arms 42 and 43, whereby to make the back contacts absolutely fixed and unyielding when the movable contacts strike them.

The movable contact fingers 32 and 33 are made of relatively thin, light springy ribbon like material, are relatively short in length, and are connected at one end, as at 45, to a short light spring member 46, which, together with arms 42 and 43, are carried by a contact block 41, connected as by screws 48, to a bracket 49, supported from the top plate as by bolts 50.

As shown in the drawings, the movable contact fingers 32 and 33, carry contact points 51 and 52, for cooperating, respectively, with the fixed contact points 31 and 38.

The armature is biased to its deenergized, or non-operative polarity position, by the means 53 and 54. Thus, the relay, as shown in Fig. 1, can be considered to be making up its back points, in which condition the movable contact point 5!, is in contact with the fixed contact point 31.

Means are provided, in accordance with this invention, to readily adjust the polar air gap between the armature and the permanent magnet pole shoes. The permanent magnets, a M, are each received in a socket member 55, which constitutes the permanent magnet pole shoes l8, and is bolted to the top plate, as by means 51, as clearly shown in Fig. 1.

The permanent magnet, as M, is received in a socket 5B in this receiving member, and is held against becoming loose by a spring locking means 59, as shown in detail in Fig. 2. This spring looking means 59 comprises a flat central portion with upturned ends 60 and 6|, drilled as at 62 and 63, to receive the ends of the permanent magnets. When the parts are assembled the upsprung ends 60 and 6! are sprung, as shown in Fig. 1, between each permanent magnet and its receiving socket, and thus the spring operates to hold the two permanent magnets in fixed position and free from all vibration and play.

Extending from the lower face of each receiv-- ing socket, as the socket 58, isa drilled hole, which receives a threaded adjusting screw 64, which bears at its lower end against one end of the pivot bearing bar 20. This screw and the corresponding one in the other socket, can be moved inwardly or outwardly to position the bearing bar 20 a greater or lesser distance from the lower face of the permanent magnet pole shoes, whereby to vary the gap between the armature and the permanent magnet pole shoes. The adjusting screws, as 64, are held in adjusted position by set screws, as 66.

From the above description it can be seen that very rigid and quite immovable back and front fixed contact fingers and contact points are provided for cooperation with movable contact fingers which are relatively short and light. Hence, in making contact with either of the fixed contact points, there is but little energy in the movable fingers to tend to 'produce vibration, or

bouncing, with respectto the fixed contact Furthermore, the armature, with its op- I points. 7 'erating'arm 21 for operating the movable contact fingers, does not carry the movable contact fingers, and hence the mass of the armature is not involved in tending to produce any bouncing, or vibration, upon making up of front, or back, points.

detail.

In Fig. 4, the movable contact fingers are shown separate, and entirely free, from the operating arm 21. It can be seen that they are formed to have a natural bias to position them in a widely spaced relation, of an extent considerably greater than the spacing between the jaw parts 30 and 3i. Thus, when these movable fingers are pressed towards each other so as to be received in the operating jaw parts, as shown in Fig. 5, there is a very considerable amount of trapped tension or pretension. This condition is shown in Fig. 5, and the operating arm 2'! is shown in its position half-way between full deenergized, and energized, positions.

In Fig. 6 is shown the position of the contacts, and associated parts, when the operating arm 27 has moved the movable contact fingers so as to pass just very slightly beyond the point where the movable point 5| touches the fixed point 31 and thus to transfer the trapped tension in the movable finger 32, to contact pressure between the two contact points in contact with each other.

In Fig. 7 the parts are shown in thepositions they assume when the back contact is fully made up. It can be seen that the operating arm 2? has moved somewhat furtherthan as shown in Fig. 6, and that the upward jaw part 35, which in Fig. 6 is still in contact with its movable contact finger is now spaced therefrom (Fig. 7) whereby to, in effect, largely-separate the mass of the armature from contributing to any tendency for the contact points to vibrate or bounce. Also, further contact pressure has been developed.

' In Fig. 8, the parts are shown in the positions assumed in moving from fully making up its back point, as shown in Fig. '7, to having just made up its front point. This corresponds to the showing in Fig. 6.

In Fig. 9 the parts are shown in the positions assumed when the front point is fully made up, and full contact pressure is realized; and this corresponds to the showing in Fig. '7, Where the back point is fully made up and full contact pressure is realized.

In Fig. 10, is a diagrammatic showing of the above described operative characteristics of the contacts of this invention. Represented along the horizontal axis AT, is armature travel, while rep resented along the vertical axis CP, is contact pressure. As seen by the curves in this figure, the

contact pressure is at a maximum at the armature position b, which is the position of the armature when the back contact is fully made up, as for instance, in the condition shown in Fig. '7. As the contact fingers move toward making up the front contact, and just before they break contact with the back contact, the contact pressure is as shown at $8, and is the pressure produced by the trapped tension in contact finger 32, and as can be seen, is about one-half of what the pressure is when the points are fully made up.

Upon a very slight further movement toward the front contact making position, the pressure on the back point falls to zero, as represented'at 69. The condition when neither fixed contact point is made up, and the movable fingers are intermediate the front and back fixed contact points, is represented in Fig. 10 at the zero portion 10 of the curve. The contact pressure curve ll, for the front "points, .is identical with the one just described. This portion Tl has a portion made up by the trapped tension, and a further portion made up by further armature travel.

Referring now to Fig. 11, there are here shown two oscillograms, the lower of which represents 7 5 contact current conditions inanimproved relay argues-o in accbrdEncewitli'tfie' present invention, while the upp r represents f e corresponding characteristics iii a convent rial type of relay; such relay is' eiie hichtliecdntact fingers are cari iedby'the'ar atur and in which there is no orete sioir or trapped tension in the contact fingers.

Referring first to the upper os'c'ill'ograin, the fduee'd by'an nte naur gcurrent of 60 "c-yelesand fiur nis'hes a suitable scale'for rear-ring" elapsed time: Thectner tracing in this os'cillogi ain are secure the amount or current name through a mei able: conta'etf eint, and hence? a measure undernxed conditions of a are settle-resistance between t e mov able contactpomtanuits ed'poin'tp The ortion 13 or the curve indicates that the contacts are fully open: and no '"curr' ent flows through the movable" contact point. In other words, there is a 'sum'eient games-"when the contact points are open to preiient all current flow. The: portion 14 of the curve-"represents current flowat its highest level, and thus represents the condition with the contacts-fully made-up, and with full pressure. In'the conventional relay, on making up. a nicvable point with'a fixed point, there is considerable \n'gbr'ation and bouncing for a corrsiderable period or time. During this. time the resistance across the points varies Widely from the minimum, when the contact pressure'is fully este li h dtte es stance e a ubst ntia ly to tha wh e contactser ull o n In the osoillogr-am, the'portion IS-of the curve, commi inse se i s. o vertical; in s varranged l e y side by i e. and onnectin he wer and i Her l t- 13" eiid tin ic e that. e a er d o t me. the on act Pelt re tan e va e bac a d forth o e maxim m. to a n mum fier thi s 'nre nts brin p o 16 f e curve, the resistance fluctuates considerably, b t Within narr l m t hanear e and an es, o r a p r df q "t o th e yc e o e 60 cycle current, from a minimum resistance, to a ver Su st n all hr iesed res s an 18-, and theip'eriod of zero current flow is represented at 19. It can be seen from this oscillogram that no current flows when the contacts are open and that, upon the movable contact touching the fixed contact, the circuit is at once closed; v reuse minimum resistance, so that, tor j entire" perioct of ebntsct closed condition, current news the circuit at a uniform, and the highest,- leveL- As a result, substantially all 'ar'cing and'burning of contacts, and mechanical wear "or the same, is obviated, and the relay is much longer lived and more dependable. Also,

the" circuits controlled, as, particularly, in the case of a'relay following a relatively fast code, are controlled much-more accurately and dependably.

U Eli-us, in applicants relay, unlike the 'c'o'nven tional relay, there is no? tendency, during mid stroke and at the time contact is made, to vibrate afres'ult it'car'i seen-from this oscillog rar'n or whip, because of the fingers being held, with trapped tension, in the operator.

I Also, the anvil effect, 1. e. the tendency for the finger to bounce off of the fixed contact so generally present in conventional constructions, is largely eliminated in applicants relay, due to the high degree of trapped tension in compari- "son with the small mass of the moving parts involved.

While the proportions, and relative amounts of movement, of the various parts of this relay, can be varied within any reasonable limits, without'depa'rting from the spirit of the present in:- vention, it should be understood that the construction described above, and the relative lightness of the'fingers, and amounts of trapped tension, and movements, are to a large extent an essential part of the present invention. While not restricting the invention to any particular set of values, one set which has been found in actual practice, to work out to distinct advantag e; may wellfbe'given. It is-a relay constructed in accordancewith this particular set of values, that produced the oscillog raph readings-'shoWn-in the lower oscillogram'of Fig. '11

In; this relayftl e full contact finger pressure is grams, while the trappedtension is 30 grams. 'ifhe travel from full contact pressure to trapped tension pressure, that is, on'Fig. 10, the horikontally measured distance from the point Uto'the point- 5}}, is 025", and the movement, measured horizontally'from the point 6,8, to the point 59, is something less than .001. Themovement over l e period where zero pressure exists, is in the order of about .01 3. The spacing between the mo ab con ac fin er and 3 e e r opiate F ss' beut I le. h n'th are. o press d. s to b received in erat 3 bu t l ou Of conta th. e r ont o ck fixe co a ts as in F a th a in tween the fingers is about1070. As indicated above, the relay of this invention is particularly adapted to be used to follow coded current, often times of a high rate, and to be energized from a track circuit. Thus, under varying'weather conditions, the level of energy applied to the relay, and depended upon to produce proper relay operation, will vary widely from time to time. Furthermore, the utmost economy in energy consumption is sought.

Under conditions such as outlined above, the usual and conventional relay is often rather unsatisfactory, and is particularly so when the level of energization falls to its minimum. Under such conditions and requirements, however, relays constructed in accordance with this invention, perform in a most satisfactory manner, and thus solve the very difiicult problem of providing arelay of satisfactory operative characteristics, even when employed so as to effect the inaxim'um of economy in energy consumption, and under conditions of widely varying degrees of ene rg' ization The above rather specific description oi one form which the present invention can assume, is given solely by way of example, and is not intended, in any manner whatsoever, in a limiting sense. It is to be understood that various modifications, adaptations and alterations may, from time to time, be applied to meet the requirements of practice, without in any manner departing from the spirit or scope of the invention, except as may be limitedv by the appended claims.

What I claim is:

In an electromagnetic relay having a pivoted armature; an elongated contact operator fixed at one end to the armature and having two spaced opposed holding jaws on the other end, a fixed contact block, a back contact finger and contact point carried by the block, a movable contact finger carried by the block and comprising, a flexible arm carried by the block and two flexible ribbons each connected at one end to the flexible arm and having their other ends extending toward said jaws and received within the jaws and strongly biased apart so as to tend to further space the jaws, a movable contact point on one flexible ribbon and positioned between the jaws and the flexible arm and opposed to the back contact point, and means for moving the armature from a position where the contact points are spaced from each other, to a position beyond the place where the contact points first touch each other.

2. In an electromagnetic device having a pivoted armature; an elongated rigid contact oper- -.ator fixed at one end to the armature and having two spaced opposed holding jaws at the other end, a fixed contact block, a rigid back contact finger and back contact point carried by the block, a flexible movable contact finger carried by the block and comprising a short flexible light arm carried by the block and two light flexible short ribbons each connected at one end to the flexible arm and having their other ends exa position where the contact points are spaced from each other to a position beyond the place where the contact points first touch each other.

3. In an electromagnetic device having a pivoted armature; an elongated rigid contact operator fixed at one end to the armature, two

spaced opposed holding jaws at the other end of the operator, a fixed contact block, two spaced rigid contact fingers and contact points carried by the block, a movable contact finger fixed to the block between the rigid fingers and comprising a flexible arm fixed to the block and two flexible ribbon contact fingers each connected at one end to the flexible arm and having their other ends extending toward said jaws and received within the jaws and strongly biased apart so as to tend to further space the jaws, a movable contact on each flexible finger and each opposed to a contact point on a'rigid finger, and means for moving the armature from a position beyond in one direction of where twoopposed contacts first touch to a position beyond in the other direction of where the other two opposed contact points first touch.

4. In an electromagnetic 'device having a pivoted armature; an elongated contact operator fixed at one end to the armature and having two spaced opposed holding jaws on the other end, a fixed contact block, a back contact finger and contact point carried by the block, a movable contact finger carried by the block and comprising, a flexible arm carried by the block and two flexible ribbons each connected at one end to the flexible arm and having their other ends extend ing toward said jaws and received within the jaws and strongly biased apart so as to tend to further space the jaws, a movable contact point on one flexible ribbon and opposed to the back contact point, and means for moving the armature from a position where the contact points are spaced from each other, to a position beyond the place where the contact points first touch each other.

5. In a contact structure for use in an electromagnetic relay of the tractive type, two spaced fixed contacts insulated from each other, a spring arm anchored at one end adjacent said fixed contacts but insulated therefrom in a position to allow its free end to swing between-such fixed contacts, two spring contacts attached to the free end of said spring arm and self-biased away from each other, an armature operated member having two spaced rigid fingers confining said two spring contact fingers within a limited space to produce an initial trapped pressure, said memher being operable between two extreme positions, in one of which positions it causes one spring contact to engage one fixed contact with a pressure determined by the added compression of the other spring contact, and in the other of which positions it causes said other spring contact to engage the other fixed contact with a pressure determined by the added compression of said one spring contact, whereby each spring contact initially contacts its respective fixed contact with an initial trapped pressure to prevent its bouncing due to the impact.

6. In an electromagnetic relay havin a pivoted armature, a contact block located to one side away from said pivoted armature, a spring arm anchored to one end to said contact block with its free end extending toward said pivoted armature, two spring members attached to the free end of said spring arm and tensioned so as to be biased away from each other, an operating arm attached to the armature and extendingtoward said contact block, said operating arm having two spaced rigid fingers grasping said two spring members for confining them to produce an initial trapped pressure, a contact point attached to one of said two spring members, and a fixed contact attached to said contact block and adapted to be engaged by said contact point on said spring member, whereby said operating arm is capable of closing and opening said contacts as it is operated to its two opposite positions, said contacts being initially made with trapped pressure equal to the tension of said spring members between said rigid fingers.

FRANK X. REES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name- Date 1,269,9l7 Field June 18, 1918 1,799,629 Lockhart et a1 Apr. 7, 1931 1,849,403 Jefierson Mar. 15, 1932 1,958,646 Snavely et a1. May 15, 1934 2,13%,448 Knos "Oct. 25, 1938 2,197,607 Brown Apr. 16, 1940 2,258,123 Merkel Oct. 7, 1941 2,333,971 Ashworth Nov. 9, 1943 2,360,664 Field Oct. 17, 1944 FOREIGN PATENTS Number Country Date 61,210 Germany Feb. 18, 1892 

